JP2722990B2 - Exhaust gas purification device for internal combustion engine - Google Patents

Exhaust gas purification device for internal combustion engine

Info

Publication number
JP2722990B2
JP2722990B2 JP5104347A JP10434793A JP2722990B2 JP 2722990 B2 JP2722990 B2 JP 2722990B2 JP 5104347 A JP5104347 A JP 5104347A JP 10434793 A JP10434793 A JP 10434793A JP 2722990 B2 JP2722990 B2 JP 2722990B2
Authority
JP
Japan
Prior art keywords
absorbent
exhaust
engine
exhaust gas
intake
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP5104347A
Other languages
Japanese (ja)
Other versions
JPH06317142A (en
Inventor
康 荒木
喜代志 小端
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Priority to JP5104347A priority Critical patent/JP2722990B2/en
Publication of JPH06317142A publication Critical patent/JPH06317142A/en
Application granted granted Critical
Publication of JP2722990B2 publication Critical patent/JP2722990B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0871—Regulation of absorbents or adsorbents, e.g. purging
    • F01N3/0885—Regeneration of deteriorated absorbents or adsorbents, e.g. desulfurization of NOx traps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/0807—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents
    • F01N3/0828—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by using absorbents or adsorbents characterised by the absorbed or adsorbed substances
    • F01N3/0842—Nitrogen oxides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/14—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system
    • F02M26/15—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the exhaust system in relation to engine exhaust purifying apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2260/00—Exhaust treating devices having provisions not otherwise provided for
    • F01N2260/14—Exhaust treating devices having provisions not otherwise provided for for modifying or adapting flow area or back-pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/04—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits concerning exhaust conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
    • F02M26/21—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system with EGR valves located at or near the connection to the intake system

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Control Of Throttle Valves Provided In The Intake System Or In The Exhaust System (AREA)
  • Exhaust Gas After Treatment (AREA)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、内燃機関の排気浄化装
置に関し、詳細にはディーゼルエンジンや希薄空燃比の
燃焼を行うガソリンエンジン等リーン空燃比の燃焼を行
う内燃機関の排気中のＮＯX 成分を効果的に除去可能な
排気浄化装置に関する。The present invention relates to relates to an exhaust purifying apparatus for an internal combustion engine, in the exhaust gas of an internal combustion engine causing combustion of gasoline engines such as lean air causing combustion of a diesel engine or a lean air-fuel ratio in particular NO X The present invention relates to an exhaust gas purification device capable of effectively removing components.

【０００２】[0002]

【従来の技術】リーン空燃比の燃焼を行う内燃機関の排
気中のＮＯX を浄化する排気浄化装置の例としては、特
開昭６２−１０６８２６号公報に記載されたものがあ
る。同公報の装置では、ディーゼルエンジンの排気通路
に、酸素存在下でＮＯX を吸収するＮＯX 吸収剤を配置
し、吸収剤のＮＯX 吸収効率が低下した時点でＮＯ X 吸
収剤への排気流入を遮断してＮＯX 吸収剤に還元剤を導
入することにより吸収したＮＯX を放出させ、還元浄化
している。2. Description of the Related Art Exhaust of an internal combustion engine that performs combustion at a lean air-fuel ratio.
NO in the airXAs an example of an exhaust purification system that purifies
One described in Japanese Unexamined Patent Publication No.
You. In the device of the publication, the exhaust passage of a diesel engine
NO in the presence of oxygenXNO that absorbsXPlace absorbent
And NO of the absorbentXNO when absorption efficiency drops XSucking
Cut off the inflow of exhaust gas to the absorbent and NOXGuide the reducing agent to the absorbent
NO absorbed by enteringXRelease and purification
doing.

【０００３】上記公報の装置は、酸素を多量に含む排気
がＮＯX 吸収剤に流入することを防止しながらＮＯX 吸
収剤に還元剤を導入することによりＮＯX 吸収剤の雰囲
気酸素濃度を低下させてＮＯX 吸収剤からＮＯX を放出
させ、還元剤によりこのＮＯ X を還元浄化している。し
かし、上記公報の装置では、ＮＯX 吸収剤からのＮＯX
放出及び還元浄化（以下ＮＯX 吸収剤の「再生」とい
う）を行う際にＮＯX 吸収剤への排気流入を遮断する必
要があるため、機関運転中にＮＯX の放出、浄化を行お
うとすると、排気系に複数のＮＯX 吸収剤を並列配置し
て順次切換えて排気流入を遮断してＮＯ X 吸収剤の再生
を行うようにして排気流路を確保する必要があり、装置
の複雑化や車両への搭載性の悪化を生じるおそれがあ
る。[0003] The apparatus disclosed in the above publication is an exhaust gas containing a large amount of oxygen.
Is NOXNO while preventing flow into the absorbentXSucking
NO by introducing a reducing agent into the absorbentXAtmosphere of absorbent
NO by lowering the oxygen concentrationXNO from absorbentXRelease
And this NO XHas been reduced and purified. I
However, in the device of the above publication, NOXNO from absorbentX
Release and reduction purification (hereinafter NOX"Regeneration" of absorbent
NO)XIt is necessary to shut off exhaust gas to the absorbent.
NO during engine operationXRelease and purify
Attempting to use multiple NOs in the exhaust systemXAbsorbents are arranged in parallel
To switch sequentially to block exhaust inflow and NO XRegeneration of absorbent
It is necessary to secure an exhaust passage by performing
May become complicated and the mountability to the vehicle may deteriorate.
You.

【０００４】一方、本願出願人は、ＮＯX 吸収剤の再生
時にある程度の量の排気を流したまま還元剤を導入して
ＮＯX 吸収剤の再生を行い、ＮＯX 吸収剤再生時にも排
気流入を遮断しない排気浄化装置を既に提案している
（特願平４−２６３８９２号）。この装置によれば、Ｎ
ＯX 吸収剤再生時にも排気流路が確保され、単一のＮＯ
X 吸収剤を用いて機関運転中にＮＯX 吸収剤の再生を行
うことができるため、複数のＮＯX 吸収剤を設ける必要
がないので装置の簡易化と搭載性の向上とを図ることが
できる。On the other hand, the applicant of the present application hasXRegeneration of absorbent
Sometimes introducing a reducing agent with a certain amount of exhaust gas flowing
NOXRegeneration of the absorbent, NOXExhausted during absorbent regeneration
We have already proposed an exhaust purification device that does not block air inflow
(Japanese Patent Application No. 4-263892). According to this device, N
OXExhaust flow path is secured even when the absorbent is regenerated, and a single NO
XNO during engine operation using absorbentXRegeneration of absorbent
Multiple NOXIt is necessary to provide an absorbent
Simplification of the equipment and improvement of the mountability
it can.

【０００５】上記特願平４−２６３８９２号に提案した
装置では、ＮＯX 吸収剤上流側の排気系に排気中の酸素
を消費する酸素消費手段を設けＮＯX 吸収剤に流入する
排気中の酸素濃度を低減し、ＮＯX 吸収剤再生時のＮＯ
X の放出を容易にしている。[0005] In the apparatus proposed in JP above Japanese Patent Application No. 4-263892, the oxygen in the exhaust gas flowing to the NO X absorbent provided the oxygen consumption means for consuming oxygen in the exhaust gas in the exhaust system of the NO X absorbent upstream reduced concentration, NO X absorbent at the time of reproduction NO
Easy X release.

【０００６】[0006]

【発明が解決しようとする課題】上記特願平４−２６３
８９２号の装置のようにＮＯX 吸収剤に排気を流したま
ま再生を行う場合、流入する排気中に含まれる酸素を消
費してＮＯX 吸収剤の雰囲気酸素濃度を低下させる必要
が生じる。上記特願平４−２６３８９２号の装置では、
機関吸気通路に吸気絞り弁を設け、エンジンブレーキ時
に吸気絞り弁を閉弁して機関吸入空気量を絞るとともに
ＮＯX 吸収剤上流側に設けた酸素消費手段に還元剤を供
給して燃焼させて排気中の酸素を消費し、ＮＯX 吸収剤
に流入する排気中の酸素濃度を低下させてＮＯX 吸収剤
の再生を行っている。SUMMARY OF THE INVENTION The aforementioned Japanese Patent Application No. 4-263 is disclosed.
When the regeneration is performed while the exhaust gas is flowing through the NO X absorbent as in the apparatus of No. 892, it is necessary to reduce the atmospheric oxygen concentration of the NO X absorbent by consuming the oxygen contained in the flowing exhaust gas. In the apparatus of Japanese Patent Application No. 4-263892,
Engine intake passage is provided an intake throttle valve, and is supplied to burn the reducing agent to the oxygen consumption means provided in the NO X absorbent upstream with and closes the intake throttle valve when the engine brake squeeze engine intake air amount consume oxygen in the exhaust, thereby reducing the oxygen concentration in the exhaust gas flowing to the NO X absorbent is carried out the regeneration of the NO X absorbent.

【０００７】ディーゼルエンジンなどリーン空燃比の燃
焼を行う機関では排気中に多量の酸素が含まれるため、
ＮＯX 吸収剤に排気を流したまま再生を行う場合、排気
中の酸素を消費するために必要となる還元剤の量は非常
に多くなり還元剤消費量が増大する問題が生じる。上記
特願平４−２６３８９２号ではＮＯX 吸収剤再生時に機
関吸入空気量を絞ることにより機関に流入する酸素量を
低減して、排気中の酸素消費に要する還元剤の量の減少
を図っている。In an engine that burns at a lean air-fuel ratio such as a diesel engine, a large amount of oxygen is contained in the exhaust gas.
When the regeneration is performed with the exhaust gas flowing through the NO X absorbent, the amount of the reducing agent required to consume the oxygen in the exhaust gas becomes extremely large, and a problem arises that the amount of the reducing agent consumed increases. In JP above Japanese Patent Application 4-263892 by reducing the amount of oxygen flowing into the engine by throttling the engine intake air amount at the time of the NO X absorbent regeneration, the aim of decreasing the amount of reducing agent required for oxygen consumption in the exhaust gas I have.

【０００８】ＮＯX 吸収剤に排気を流したまま再生を行
う場合には、機関吸入空気量を減少させるほど排気中の
酸素消費に要する還元剤の量が減少する。しかし、上記
特願平４−２６３８９２号の装置のように、吸気絞り弁
を用いて機関吸入空気量を低減しようとした場合、機関
吸入空気量を大幅に低減する事ができず、還元剤消費量
の十分な低減を図ることができない問題が生じる。[0008] When reproducing while flowing exhaust into the NO X absorbent, the amount of reducing agent required for oxygen consumption in the exhaust gas as reducing the engine intake air amount decreases. However, when the engine intake air amount is reduced by using an intake throttle valve as in the device disclosed in Japanese Patent Application No. 4-263892, the engine intake air amount cannot be significantly reduced, and the reducing agent consumption is reduced. A problem arises in that the amount cannot be sufficiently reduced.

【０００９】すなわち、上記特願平４−２６３８９２号
の装置ではエンジンブレーキの際に吸気シャッターバル
ブの絞り量を大きくとり過ぎると、吸気マニホルドの負
圧が過度に増大し吸入行程のシリンダ内負圧が大きくな
る。このため、エンジンブレーキ時に運転者の予期した
以上の減速トルクが発生し、減速ショックが大きくなっ
て運転感覚が悪化するのみならず、シリンダ負圧の増大
によりピストンリングとシリンダ壁との間から潤滑油が
燃焼室内に入り込みエンジンの潤滑油消費量が増大する
問題が生じてしまう。このため、吸気シャッターバルブ
による機関吸入空気量の絞り量をある程度以上大きくと
ることはできず還元剤の消費量を十分に低減することが
困難になっている。That is, in the device disclosed in Japanese Patent Application No. 4-263892, if the throttle amount of the intake shutter valve is set too large during engine braking, the negative pressure of the intake manifold increases excessively and the negative pressure in the cylinder during the intake stroke increases. Becomes larger. As a result, when the engine brakes, deceleration torque more than expected by the driver is generated, and the deceleration shock becomes large, which deteriorates the driving sensation. In addition, the increase in cylinder negative pressure causes lubrication between the piston ring and the cylinder wall. There is a problem that the oil enters the combustion chamber and the amount of lubricating oil consumed by the engine increases. For this reason, the throttle amount of the engine intake air amount by the intake shutter valve cannot be increased to a certain degree or more, and it is difficult to sufficiently reduce the consumption amount of the reducing agent.

【００１０】本発明は、上述の問題に鑑み、運転間隔の
悪化や機関潤滑油消費量の増大を生じることなくＮＯX
吸収剤再生時の還元剤消費量を低減することができる排
気浄化装置を提供することを目的としている。[0010] The present invention has been made in view of the above problems, without causing an increase in the degradation and Engine Oil consumption headway NO X
It is an object of the present invention to provide an exhaust gas purification device capable of reducing the amount of reducing agent consumed during regeneration of an absorbent.

【００１１】[0011]

【課題を解決するための手段】本発明によれば、リーン
空燃比の燃焼を行う内燃機関の排気通路に、流入排気の
空燃比がリーンのときにＮＯX を吸収し流入排気の酸素
濃度が低下したときに吸収したＮＯX を放出するＮＯX
吸収剤を配置して排気中のＮＯX を吸収させ、前記ＮＯ
X 吸収剤に還元剤を供給することにより排気中の酸素濃
度を低下させ、ＮＯX 吸収剤から吸収したＮＯX を放出
させるとともに該ＮＯX を還元浄化する内燃機関の排気
浄化装置において、前記ＮＯX 吸収剤に還元剤を供給す
る際に、機関排気の少なくとも一部を機関吸気通路に還
流させる手段を備えたことを特徴とする内燃機関の排気
浄化装置が提供される。According to the present invention, in order to solve the problems], in an exhaust passage of an internal combustion engine causing combustion of lean air-fuel ratio, the air-fuel ratio of the inflowing exhaust gas is the oxygen concentration of the inflowing exhaust absorbs NO X when the lean NO X to release the absorbed NO X when lowered
By placing the absorbent to absorb NO X in the exhaust gas, the NO
Lowering the oxygen concentration in the exhaust gas by supplying a reducing agent to X absorbent, the exhaust purification system of an internal combustion engine to reduce and purify the NO X with the release of NO X absorbed from the NO X absorbent, the NO An exhaust gas purification device for an internal combustion engine is provided, which comprises means for recirculating at least a part of engine exhaust to an engine intake passage when supplying a reducing agent to an X absorbent.

【００１２】[0012]

【作用】ＮＯX 吸収剤再生時に機関排気を吸気側に還流
させることにより、吸気マニホルドの負圧を増大させる
ことなく外部から機関に吸入される新気の量が低減され
る。このため、新気の量を大幅に低減した場合でも潤滑
油の消費量増大や運転感覚の悪化を伴うことなく還元剤
消費量が大幅に低減される。[Action] the NO X absorbent during regeneration by refluxing the engine exhaust to the intake side, the amount of fresh air drawn into the engine from the outside without increasing the negative pressure in the intake manifold is reduced. For this reason, even when the amount of fresh air is significantly reduced, the consumption of the reducing agent is significantly reduced without increasing the consumption of the lubricating oil or deteriorating the driving feeling.

【００１３】[0013]

【実施例】以下、添付図面を参照して本発明の実施例に
ついて説明する。図１は本発明の内燃機関の排気浄化装
置の一実施例の構成を示す図である。図１において、１
はディーゼルエンジン、２はエンジンの吸気管、３はエ
ンジンの排気管を示す。エンジンの吸気管２には吸気シ
ャッターバルブ６が設けられている。また、排気管３に
はＮＯX 吸収剤１５を収容したケーシングが接続されて
おり、ＮＯX 吸収剤１５の下流側の排気管３には、排気
シャッターバルブ８が設けられており、さらに本実施例
では、排気管３のＮＯX 吸収剤１５上流側部分と吸気管
２の吸気シャッターバルブ６下流部分とを接続する排気
再循環のためのＥＧＲ通路１１が設けられている。図１
に１２で示すのはＥＧＲ通路１１上に設けられたＥＧＲ
弁である。ＥＧＲ弁１２の弁体１２ａには負圧アクチュ
エータ１３が接続され、ＥＧＲ弁１２の作動を制御して
いる。負圧アクチュエータ１３はダイヤフラム１３ａに
より形成される負圧室１３ｂとダイヤフラム１３ａを押
圧付勢するばね１３ｃとを備えており、ＥＧＲ弁１２の
弁体１２ａはダイヤフラム１３ａに連結されている。ば
ね１３ｃは常時弁体１２が弁座に密着する方向にダイヤ
フラム１３ａを押圧しており、通常時はＥＧＲ通路１１
は弁体１２により閉塞され、ＥＧＲ通路１１から吸気通
路２には排気は還流しないが、通常運転中に負圧アクチ
ュエータ１３の負圧室１３ｂに適宜な負圧源から運転状
態に応じて負圧を供給することによりＥＧＲ弁１２を開
弁させ排気再循環を行うことができる。さらに、本実施
例ではばね１３ｃの付勢力は、吸気管２内の圧力が低下
してＥＧＲ通路１１内の排気圧力と吸気圧力との差が所
定値以上になったときに排気がばね１３ｃの付勢力に抗
して弁体１２ａを押し上げて吸気管２内に流入するよう
に適宜に設定されている。Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing the configuration of an embodiment of the exhaust gas purifying apparatus for an internal combustion engine of the present invention. In FIG. 1, 1
Denotes a diesel engine, 2 denotes an intake pipe of the engine, and 3 denotes an exhaust pipe of the engine. The intake pipe 2 of the engine is provided with an intake shutter valve 6. Further, a casing accommodating the NO X absorbent 15 is connected to the exhaust pipe 3, and an exhaust shutter valve 8 is provided in the exhaust pipe 3 downstream of the NO X absorbent 15. examples, an EGR passage 11 for exhaust gas recirculation for connecting the NO X absorbent 15 upstream portion of the exhaust pipe 3 and the intake shutter valve 6 downstream portion of the intake pipe 2 is provided. FIG.
Reference numeral 12 denotes an EGR provided on the EGR passage 11.
It is a valve. A negative pressure actuator 13 is connected to a valve body 12a of the EGR valve 12, and controls the operation of the EGR valve 12. The negative pressure actuator 13 includes a negative pressure chamber 13b formed by the diaphragm 13a and a spring 13c for pressing and biasing the diaphragm 13a, and the valve element 12a of the EGR valve 12 is connected to the diaphragm 13a. The spring 13c constantly presses the diaphragm 13a in a direction in which the valve body 12 comes into close contact with the valve seat.
Is closed by the valve body 12 and the exhaust gas does not recirculate from the EGR passage 11 to the intake passage 2. However, during the normal operation, the negative pressure is supplied to the negative pressure chamber 13b of the negative pressure actuator 13 from an appropriate negative pressure source according to the operation state. Supply, the EGR valve 12 is opened to perform exhaust gas recirculation. Further, in this embodiment, the urging force of the spring 13c is such that when the pressure in the intake pipe 2 decreases and the difference between the exhaust pressure and the intake pressure in the EGR passage 11 becomes a predetermined value or more, the exhaust of the spring 13c The valve body 12a is appropriately set so as to push up the valve body 12a against the urging force and flow into the intake pipe 2.

【００１４】吸気シャッターバルブ６と排気シャッター
バルブ８は全開時に抵抗の少ないバタフライ弁等の形式
の弁とされ、エンジンの通常運転時には全開に維持され
吸気抵抗や排気抵抗を生じない。また、吸気シャッター
バルブ６は負圧アクチュエータ、ステッパモータ等の適
宜な形式のアクチュエータ７を備え、後述のＮＯX 吸収
剤１５再生操作時に所定開度まで閉弁され吸気管２を絞
りＮＯX 吸収剤１５を通過する排気流量を低減する。排
気シャッターバルブ８は、同様に適宜な形式のアクチュ
エータ９を備え、ＮＯX 吸収剤１５再生操作時に所定開
度まで閉弁され排気管３を絞り排気圧力を上昇させてＥ
ＧＲ通路１１を通って吸気管２に還流する排気の流量を
増大させる。The intake shutter valve 6 and the exhaust shutter valve 8 are valves of a type such as a butterfly valve having low resistance when fully opened, and are kept fully open during normal operation of the engine so that intake resistance and exhaust resistance are not generated. The intake shutter valve 6 is negative pressure actuator includes a suitable form of actuator 7, such as stepper motors, later of the NO X absorbent 15 reproducing operation when is closed to the predetermined opening degree intake pipe 2 to stop the NO X absorbent 15 to reduce the flow rate of exhaust gas. Exhaust shutter valve 8 is provided with an actuator 9 for similarly appropriate form, NO X absorbent 15 while being closed to the predetermined opening degree at the time of the regenerating operation to increase the exhaust pressure throttle in the exhaust pipe 3 E
The flow rate of exhaust gas flowing back to the intake pipe 2 through the GR passage 11 is increased.

【００１５】図に３０で示すのはエンジン１の電子制御
ユニット（ＥＣＵ）である。ＥＣＵ３０はＣＰＵ２１、
ＲＡＭ２２、ＲＯＭ２３及び入力ポート２４、出力ポー
ト２５を相互に双方向バス２６で接続した構成の公知の
形式のディジタルコンピュータからなり、エンジン１の
燃料噴射弁４を制御して燃料噴射量制御等の通常制御を
行うほか、本実施例ではＮＯX 吸収剤１５の再生操作の
ための燃料噴射制御や吸気シャッターバルブ６、排気シ
ャッターバルブ８の開閉制御を行っている。これらの制
御のためＥＣＵ３０の入力ポートには、エンジン回転
数、アクセル開度、排気温度等の信号がそれぞれ図示し
ないセンサから入力されている。In FIG. 1, reference numeral 30 denotes an electronic control unit (ECU) of the engine 1. The ECU 30 is a CPU 21,
A known type of digital computer having a configuration in which a RAM 22, a ROM 23, an input port 24, and an output port 25 are connected to each other by a bidirectional bus 26, controls the fuel injection valve 4 of the engine 1 to control the fuel injection amount. in addition to performing control is performed fuel injection control and the intake shutter valve 6 for the regenerating operation of the NO X absorbent 15, the opening and closing control of the exhaust shutter valve 8 in this embodiment. For these controls, signals such as an engine speed, an accelerator opening, and an exhaust gas temperature are input from input sensors (not shown) to input ports of the ECU 30.

【００１６】ＮＯX 吸収剤１５は例えばアルミナを担体
とし、この担体上に例えばカリウムＫ，ナトリウムＮa
，リチウムＬi ，セシウムＣs のようなアルカリ金
属、バリウムＢa , カルシウムＣa のようなアルカリ土
類、ランタンＬa ，イットリウムＹのような希土類から
選ばれた少なくとも一つと、白金Ｐt のような貴金属と
が担持されている。このＮＯX 吸収剤１５は流入する排
気の空燃比がリーンの場合にはＮＯX を吸収し、酸素濃
度が低下するとＮＯX を放出するＮＯX の吸放出作用を
行う。[0016] the NO X absorbent 15, for example alumina as a carrier, with, for example, on the carrier K, sodium Na
, Lithium Li, alkali metal such as cesium Cs, alkaline earth such as barium Ba and calcium Ca, and rare earth such as lanthanum La and yttrium Y, and a noble metal such as platinum Pt. Have been. This the NO X absorbent 15 absorbs NO X in the case the air-fuel ratio of the exhaust gas flowing is lean, the oxygen concentration is carried out to absorbing and releasing action of the NO X that releases NO X when lowered.

【００１７】なお、上述の排気空燃比とは、ここではＮ
ＯX 吸収剤１５の上流側の排気通路やエンジン燃焼室、
吸気通路等にそれぞれ供給された空気量の合計と燃料の
合計の比を意味するものとする。従って、ＮＯX 吸収剤
１５の上流側排気通路や吸気通路に燃料や還元剤または
空気が供給されない場合には排気空燃比はエンジンの運
転空燃比（エンジン燃焼室内の燃焼における空燃比）と
等しくなる。The above-described exhaust air-fuel ratio is defined as N
O X on the upstream side of the absorber 15 exhaust passage and an engine combustion chamber,
It means the ratio of the sum of the amount of air supplied to the intake passage or the like and the sum of the fuel. Thus, NO X in the upstream side exhaust passage and an intake passage of the absorbent 15 fuel or reducing agent or the exhaust air-fuel ratio when the air is not supplied is equal to the operating air-fuel ratio of the engine (air-fuel ratio in the combustion in the engine combustion chamber) .

【００１８】本実施例では、ディーゼルエンジンが使用
されているため、通常運転時の排気空燃比はリーンであ
り、ＮＯX 吸収剤１５は排気中のＮＯX の吸収を行う。
また、後述の操作により排気中の酸素濃度が低下する
と、ＮＯX 吸収剤１５は吸収したＮＯX の放出を行う。
この吸放出作用の詳細なメカニズムについては明らかで
ない部分もある。しかし、この吸放出作用は図２に示す
ようなメカニズムで行われているものと考えられる。次
にこのメカニズムについて担体上に白金Ｐt およびバリ
ウムＢa を担持させた場合を例にとって説明するが他の
貴金属、アルカリ金属、アルカリ土類、希土類を用いて
も同様なメカニズムとなる。[0018] In this embodiment, since the diesel engine is used, the exhaust air-fuel ratio during normal operation is lean, NO X absorbent 15 performs the absorption of the NO X in the exhaust gas.
Further, when the oxygen concentration in the exhaust gas decreases by the operation described below, NO X absorbent 15 performs the release of the absorbed NO X.
The detailed mechanism of this absorption / release action is not clear in some parts. However, it is considered that this absorption / release action is performed by a mechanism as shown in FIG. Next, this mechanism will be described by taking as an example a case where platinum Pt and barium Ba are supported on a carrier, but the same mechanism can be obtained by using other noble metals, alkali metals, alkaline earths and rare earths.

【００１９】すなわち、流入排気がかなりリーンになる
と流入排気中の酸素濃度が大巾に増大し、図２(A) に示
されるようにこれら酸素Ｏ2 がＯ2 - またはＯ2-の形で
白金Ｐt の表面に付着する。一方、流入排気中のＮＯは
白金Ｐt の表面上でこのＯ2 - またはＯ2-と反応し、Ｎ
Ｏ2 となる（２ＮＯ＋Ｏ2 →２ＮＯ2 ) 。次いで生成さ
れたＮＯ2 の一部は白金Ｐｔ上で酸化されつつ吸収剤内
に吸収されて酸化バリウムＢａＯと結合しながら図２
(A) に示されるように硝酸イオンＮＯ3 - の形で吸収剤
内に拡散する。このようにしてＮＯX がＮＯX 吸収剤１
５内に吸収される。That is, the inflow exhaust gas becomes considerably lean.
And the oxygen concentration in the inflowing exhaust gas greatly increased, as shown in Fig. 2 (A).
These oxygen OTwoIs OTwo -Or O2-In the form of
It adheres to the surface of platinum Pt. On the other hand, NO in the inflow exhaust gas is
This O on the surface of platinum PtTwo -Or O2-Reacts with N
OTwo(2NO + OTwo→ 2NOTwo ). Then generated
NOTwoSome of the oxygen is oxidized on platinum Pt and
While being combined with barium oxide BaO
As shown in (A), nitrate ion NOThree -Absorbent in the form of
Spreads in. NO in this wayXIs NOXAbsorbent 1
5 is absorbed.

【００２０】従って、流入排気中の酸素濃度が高い限り
白金Ｐt の表面でＮＯ2 が生成され、吸収剤のＮＯX 吸
収能力が飽和しない限りＮＯ2 が吸収剤内に吸収されて
硝酸イオンＮＯ3 - が生成される。これに対して流入排
気中の酸素濃度が低下してＮＯ2 の生成量が減少すると
反応が逆方向（ＮＯ3 - →ＮＯ2 ）に進み、吸収剤内の
硝酸イオンＮＯ3 - がＮＯ2 の形で吸収剤から放出され
る。すなわち、流入排気中の酸素濃度が低下するとＮＯ
X 吸収剤１５からＮＯX が放出されることになる。Accordingly, as long as the oxygen concentration in the inflowing exhaust gas is high, NO 2 is generated on the surface of the platinum Pt, and as long as the NO x absorption capacity of the absorbent is not saturated, NO 2 is absorbed in the absorbent and nitrate ions NO 3 - is generated. On the other hand, when the oxygen concentration in the inflowing exhaust gas decreases and the NO 2 generation amount decreases, the reaction proceeds in the reverse direction (NO 3 − → NO 2 ), and the nitrate ion NO 3 − in the absorbent becomes NO 2 Released from the absorbent in form. That is, when the oxygen concentration in the inflow exhaust gas decreases, NO
NO X will be released from the X absorbent 15.

【００２１】一方、流入排気中にＨＣ，ＣＯ等の還元成
分が存在すると、これらの成分は白金Ｐt 上の酸素Ｏ2
- またはＯ2-と反応して酸化され、排気中の酸素を消費
して排気中の酸素濃度を低下させる。また、排気中の酸
素濃度低下によりＮＯX 吸収剤１５から放出されたＮＯ
2 は図２(B) に示すようにＨＣ，ＣＯと反応して還元さ
れる。このようにして白金Ｐt の表面上にＮＯ2 が存在
しなくなると吸収剤から次から次へとＮＯ2 が放出され
る。従って流入排気中のＨＣ，ＣＯ成分が存在すると短
時間のうちにＮＯX 吸収剤１５からＮＯX が放出され、
還元されることになる。On the other hand, if reducing components such as HC and CO are present in the inflowing exhaust gas, these components become oxygen O 2 on platinum Pt.
- or it is reacted with oxide and O 2-, lowering the oxygen concentration in the exhaust to consume oxygen in the exhaust. Also, NO released from the NO x absorbent 15 due to a decrease in the oxygen concentration in the exhaust gas
2 is reduced by reacting with HC and CO as shown in FIG. 2 (B). When NO 2 is no longer present on the surface of the platinum Pt, NO 2 is released from the absorbent one after another. Accordingly HC in the inflowing exhaust gas, NO X from the NO X absorbent 15 in a short time when the CO component is present is released,
Will be reduced.

【００２２】すなわち、流入排気中のＨＣ，ＣＯは、ま
ず白金Ｐt 上のＯ2 - またはＯ2-と直ちに反応して酸化
され、次いで白金Ｐt 上のＯ2 - またはＯ2-が消費され
てもまだＨＣ，ＣＯが残っていればこのＨＣ，ＣＯによ
って吸収剤から放出されたＮＯX および機関から排出さ
れたＮＯX が還元される。従って、エンジン運転中にＮ
ＯX の放出、還元（再生）を行うためにＮＯX 吸収剤に
供給すべき還元剤の量は、酸化による酸素消費により排
気中の酸素濃度を充分に低下させるのに必要な量とＮＯ
X 吸収剤１５から放出される全ＮＯX を還元するのに必
要な量との合計となる。しかし、ディーゼルエンジンで
は排気の空燃比は常にリーンであるため、ＮＯX 吸収剤
１５に排気を流しながらＮＯX の放出、還元を行おうと
すると、排気中の酸素を消費するための還元剤の量が非
常に大きくなる。このため、本実施例ではＮＯX 吸収剤
１５の再生時に吸気管２に設けた吸気シャッターバルブ
６を閉弁して外部からエンジン１に吸入される新気の量
を低減するとともに、排気管３に設けた排気シャッター
バルブ８を閉弁してＥＧＲ通路１１を介して吸気シャッ
ターバルブ６の下流側の吸気管に排気を再循環させてＮ
ＯX 吸収剤に流入する酸素の量を低減している。[0022] That is, HC in the inflowing exhaust gas, CO, first O 2 on the platinum Pt - immediately react with oxidized or O 2-, and then on the platinum Pt O 2 - or O 2- is consumed the HC, NO X discharged from the released NO X and the engine from the absorbent by CO is reduced even yet HC, any remaining CO is. Therefore, during engine operation, N
O X release, the amount of reduction (regeneration) reducing agent to be supplied to the NO X absorbent in order to perform, the amount and NO required to reduce sufficiently the oxygen concentration in the exhaust gas by the oxygen consumption by oxidation
This is the sum of the amount required to reduce all NO X released from the X absorbent 15. However, the amount for the air-fuel ratio of the exhaust gas in a diesel engine is always lean, NO X absorbent 15 release of the NO X while flowing exhaust, and if you try to reduction, a reducing agent for consuming oxygen in the exhaust Becomes very large. Therefore, while reducing the amount of fresh air drawn from the outside into the engine 1 by closing the intake shutter valve 6 provided in the intake pipe 2 at the time of reproduction of the NO X absorbent 15 in this embodiment, the exhaust pipe 3 The exhaust shutter valve 8 is closed, and the exhaust gas is recirculated through the EGR passage 11 to the intake pipe on the downstream side of the intake shutter valve 6 so that N
The amount of oxygen flowing into the O X absorbent is reduced.

【００２３】吸気シャッターバルブ６閉弁時に排気再循
環を行うことにより排気の大部分はＮＯX 吸収剤１５上
流側から吸気シャッターバルブ６下流側に還流され、吸
気シャッターバルブ６から流入する少量の新気と混合し
てエンジン１に吸入されることになり、還流する排気の
量を適宜に設定することによりエンジン１に吸入される
吸気の量を過度に削減することなく新気の流入を大幅に
低減することができる。このため、本実施例によれば吸
気負圧が過度に増大して潤滑油消費量の増大や運転感覚
の悪化が生じることを防止しながら流入する酸素を消費
するための還元剤の量を低減することが可能となる。[0023] Most of the exhaust by performing the exhaust gas recirculation during the intake shutter valve 6 closed is returned from the NO X absorbent 15 upstream the intake shutter valve 6 downstream, a small amount of new flowing from the intake shutter valve 6 The intake air is mixed with the air and is taken into the engine 1. By appropriately setting the amount of the recirculated exhaust gas, the inflow of the fresh air can be largely reduced without excessively reducing the amount of the intake air taken into the engine 1. Can be reduced. For this reason, according to the present embodiment, the amount of the reducing agent for consuming the inflowing oxygen is reduced while preventing the intake negative pressure from excessively increasing and increasing the lubricating oil consumption and deteriorating the driving feeling. It is possible to do.

【００２４】なお、本実施例では、ＮＯX 吸収剤１５へ
供給する還元剤としてはエンジン１の燃料（軽油）を使
用し、吸気シャッターバルブ６閉弁時に燃料噴射弁４か
ら通常運転時と同様に燃焼室内に燃料を噴射することに
よりＮＯX 吸収剤１５への還元剤供給を行う。この時燃
料噴射弁４からの燃料噴射量は、吸気シャッターバルブ
６から流入する新気中の酸素を全部消費するとともに、
ＮＯX 吸収剤１５に吸収されたＮＯX を還元するのに必
要な量とされる。[0024] In this embodiment, the reducing agent supplied to the NO X absorbent 15 using fuel of the engine 1 (light oil), as in normal operation from the fuel injection valve 4 during the intake shutter valve 6 closed performing a reducing agent supply to the NO X absorbent 15 by injecting fuel into the combustion chamber. At this time, the fuel injection amount from the fuel injection valve 4 consumes all the oxygen in the fresh air flowing from the intake shutter valve 6, and
The amount is required to reduce the NO X absorbed by the NO X absorbent 15.

【００２５】本実施例では排気再循環を行うことによ
り、吸気シャッターバルブ６のみにより吸気を絞る場合
に較べて新気の流入を約１／３に低減することが可能に
なっており、酸素消費のための還元剤の量もこれに応じ
て低減される。次に、本実施例の排気浄化装置の作用に
ついて説明する。本実施例では、ＥＣＵ３０はＮＯX 吸
収剤１５の再生操作実行条件が成立した時にのみＮＯX
吸収剤１５の再生操作を行う。ここで、本実施例のＮＯ
X 吸収剤の再生実行条件は、（１）運転者がアクセル操
作をしておらず、かつエンジン回転数が所定値以上であ
ること（すなわち、エンジンブレーキの状態であるこ
と）、（２）エンジン排気温度が所定値以上であるこ
と、（３）ＮＯX 吸収剤のＮＯ X 吸収量が所定値以上に
なっていること、であり上記の条件が全て成立している
場合にのみＮＯX 吸収剤の再生操作が行われる。In this embodiment, the exhaust gas is recirculated.
When the intake air is throttled only by the intake shutter valve 6
To reduce the inflow of fresh air to about 1/3
And the amount of reducing agent for oxygen consumption depends on this
Is reduced. Next, the operation of the exhaust gas purification apparatus of this embodiment will be described.
explain about. In the present embodiment, the ECU 30XSucking
NO only when the condition for executing the regeneration operation of the absorbent 15 is satisfiedX
The regeneration operation of the absorbent 15 is performed. Here, NO in this embodiment
XThe conditions for executing the regeneration of the absorbent are as follows: (1) The driver operates the accelerator.
Not working and the engine speed is higher than the specified value.
(That is, the engine
And (2) that the engine exhaust temperature is higher than a predetermined value.
And (3) NOXAbsorbent NO XAbsorption amount exceeds a specified value
And all of the above conditions are met
NO only ifXAn absorbent regeneration operation is performed.

【００２６】ＮＯX 吸収剤の再生をエンジン減速時にの
み行うのは（上記条件（１））、再生時には吸気シャッ
ターバルブと排気シャッターバルブとを閉じて吸入空気
量を低減する必要があるため、通常運転中に再生を行う
とトルクショックを生じ運転性が悪化するためである。
また、排気温度が所定値以上（上記条件（２））とする
のは、ＮＯX 吸収剤がＮＯX 放出、還元作用の活性化す
る活性化温度に達していることが必要だからである。さ
らに、ＮＯX 吸収剤のＮＯX 吸収量が所定値以上になっ
ていること（上記条件（３））を再生実行条件としてい
るのは頻繁な再生操作を避けて真に再生が必要な場合に
のみ再生操作を行うようにするためである。[0026] NO for the regeneration of X absorbent performed only when the engine deceleration (the condition (1)), since the time of reproduction, it is necessary to reduce the amount of intake air by closing the exhaust shutter valve and the intake shutter valve normally This is because if the regeneration is performed during operation, a torque shock occurs and the operability deteriorates.
Further, exhaust gas temperature is above a predetermined value for a (the condition (2)) is, NO X absorbent is NO X emission is because must have reached the activation temperature to activate the reducing action. Further, when the NO X absorption of the NO X absorbent that is equal to or higher than a predetermined value (the condition (3)) required to reproduce execution conditions are you doing truly reproduced avoiding frequent regeneration operations This is for performing the playback operation only.

【００２７】なお、ＮＯX 吸収剤のＮＯX 吸収量は、例
えば単位時間当たりのエンジンからのＮＯX の排出量を
予めエンジン負荷（アクセル開度）とエンジン回転数等
の関数としてＥＣＵ３０のＲＯＭ２３に記憶しておき、
一定時間毎にアクセル開度と回転数とから上記関数によ
りＮＯX 排出量を求め、これに一定の係数を乗じたもの
を上記一定時間内のＮＯX 吸収剤のＮＯX 吸収量として
積算することにより求められる。It should be noted, NO X absorption of the NO X absorbent, for example, advance the engine load emissions of the NO X from the engine per unit time (accelerator opening) to ROM23 the ECU30 as a function of engine speed, etc. Remember,
Seeking NO X emissions by the function of the accelerator opening and the rotational speed at regular intervals, which in integrating the multiplied by the constant factor as NO X absorption of the NO X absorbent in said predetermined time Required by

【００２８】上記再生条件の全てが成立している場合、
ＥＣＵ３０は吸気シャッターバルブ６のアクチュエータ
７と排気シャッターバルブ８のアクチュエータ９とを駆
動し、吸気シャッターバルブ６と排気シャッターバルブ
８とを閉弁する。吸気シャッターバルブ６の閉弁により
吸気管２からエンジンに吸入される空気量が絞られ、流
入する新気の量が低減される。また、吸気シャッターバ
ルブ６の閉弁によりシャッターバルブ６下流側の吸気管
負圧が増大するが、同時に排気シャッターバルブ８が閉
弁され、排気圧力が増大するため、ＥＧＲ弁１２の弁体
１２ａには排気管圧力と吸気管負圧との差圧による力が
作用し、負圧アクチュエータ１３の負圧室１３ｂに負圧
が供給されていない場合でも弁体１２ａは弁座から離間
してＥＧＲ通路１１から吸気管２に排気が流入する。When all of the above reproduction conditions are satisfied,
The ECU 30 drives the actuator 7 of the intake shutter valve 6 and the actuator 9 of the exhaust shutter valve 8 to close the intake shutter valve 6 and the exhaust shutter valve 8. By closing the intake shutter valve 6, the amount of air taken into the engine from the intake pipe 2 is reduced, and the amount of fresh air flowing in is reduced. Further, although the intake pipe negative pressure on the downstream side of the shutter valve 6 increases due to the closing of the intake shutter valve 6, the exhaust shutter valve 8 is simultaneously closed and the exhaust pressure increases. The valve body 12a is separated from the valve seat and the EGR passage is operated even when a negative pressure is not supplied to the negative pressure chamber 13b of the negative pressure actuator 13 due to a force caused by a differential pressure between the exhaust pipe pressure and the intake pipe negative pressure. Exhaust gas flows into the intake pipe 2 from 11.

【００２９】このため、吸気シャッターバルブ６を閉じ
て大幅に新気の流入を低減した場合でもエンジンの吸気
負圧は一定値以上には増大せず潤滑油消費の増大や運転
感覚の悪化は生じない。また、ＥＣＵ３０は吸気シャッ
ターバルブ６の閉弁と同時に燃料噴射弁４からの燃料噴
射量を予め設定された量に制御する。この燃料噴射量
は、閉弁状態の吸気シャッターバルブ６を通過して流入
する新気中の全酸素を消費するのに必要な量と、ＮＯX
吸収剤１５に吸収されたＮＯX を還元するのに必要な量
との和に設定される。なお、ＮＯX 吸収剤に吸収された
ＮＯX の還元に必要とされる燃料量は新気中の酸素を消
費するのに必要とされる燃料量に較べて少なく、ＮＯX
吸収剤再生時の燃料（還元剤）消費量は実質的には流入
する新気の量により決定される。また、吸気シャッター
バルブ６閉弁時にはバルブ６を通る流れはチョークして
おり流入する新気の量は吸気マニホルドの負圧により決
まるため、本実施例ではエンジン回転数にかかわらず略
一定流量となる。このため、ＮＯX 吸収剤１５再生時の
燃料噴射弁４からの燃料噴射量はエンジン回転数にかか
わらず一定値に設定することができる。For this reason, even when the intake shutter valve 6 is closed to greatly reduce the inflow of fresh air, the intake negative pressure of the engine does not increase beyond a certain value, so that the consumption of lubricating oil increases and the driving feeling deteriorates. Absent. The ECU 30 controls the fuel injection amount from the fuel injection valve 4 to a preset amount at the same time as the closing of the intake shutter valve 6. This fuel injection amount is an amount necessary for consuming all the oxygen in the fresh air flowing through the intake shutter valve 6 in the closed state, and NO X
It is set to the sum of the amount required to reduce the NO X absorbed by the absorbent 15. The fuel amount required for reduction of the NO X absorbed in the NO X absorbent is less than the amount of fuel required to consume the oxygen in the fresh air, NO X
The fuel (reducing agent) consumption during regeneration of the absorbent is substantially determined by the amount of fresh air flowing in. When the intake shutter valve 6 is closed, the flow through the valve 6 is choked, and the amount of fresh air flowing in is determined by the negative pressure of the intake manifold. Therefore, in this embodiment, the flow rate is substantially constant regardless of the engine speed. . Therefore, the fuel injection amount from the NO X absorbent 15 during reproduction of the fuel injection valve 4 can be set to a constant value irrespective of the engine speed.

【００３０】上記のように、新気の量を低減して燃焼室
内に燃料を噴射することにより、噴射された燃料は気筒
内で燃焼するとともに、気筒内で燃焼しなかった燃料も
ＮＯ X 吸収剤の触媒作用により燃焼するため排気中の酸
素が消費され、上述のＮＯX吸収剤からのＮＯX の放
出、還元が行われる。上記のＮＯX 吸収剤の再生操作は
再生操作が所定時間実行された場合、または運転状態の
変化により上記の再生操作実行条件が成立しなくなった
場合に終了する。再生操作が終了したと判断された場
合、ＥＣＵ３０は吸気シャッターバルブ６と排気シャッ
ターバルブ８とを開弁し、通常の燃料噴射制御を再開す
る。これにより、ＥＧＲ弁１２は閉弁し、エンジン１は
通常の運転状態に復帰する。As described above, the amount of fresh air is reduced to
By injecting fuel into the cylinder, the injected fuel is
As well as fuel that did not burn in the cylinder
NO XAcids in the exhaust due to combustion by the catalysis of the absorbent
Element is consumed and the above-mentioned NOXNO from absorbentXRelease
Exit and return. NO aboveXThe regeneration operation of the absorbent
If the regeneration operation has been performed for a predetermined time or
The regeneration operation execution conditions above are no longer satisfied due to changes
If it ends. If it is determined that the playback operation has ended
ECU 30, the intake shutter valve 6 and the exhaust
Open the fuel valve 8 and restart normal fuel injection control
You. As a result, the EGR valve 12 closes, and the engine 1
Return to normal operation.

【００３１】なお、上記の実施例ではＮＯX 吸収剤再生
時の燃料噴射量は一定値に制御しているが、実際には排
気とともに噴射された燃料の一部も吸気側に還流しＮＯ
X 吸収剤再生操作開始時から時間が経過するにつれて必
要とされる燃料の量は減少する。このため、ＮＯX 吸収
剤１５の下流側の排気管に排気中の酸素濃度を検出する
酸素濃度センサを配置し、ＮＯX 吸収剤１５を通過する
排気中の酸素濃度が所定レベルに維持されるように（排
気空燃比がかなりリッチになるように）ＮＯX吸収剤再
生時の燃料噴射量をフィードバック制御するようにすれ
ば燃料供給量を低減することができる。[0031] The fuel injection amount at the time of the NO X absorbent regeneration in the above embodiment is controlled to a constant value, but actually a part of the fuel injected with the exhaust gas also flows back to the intake side NO
As the time elapses from the start of the X absorbent regeneration operation, the amount of fuel required decreases. Therefore, the oxygen concentration in the exhaust oxygen concentration sensor for detecting oxygen concentration in the exhaust to the exhaust pipe on the downstream side of the NO X absorbent 15 is disposed, passes through the NO X absorbent 15 is maintained at a predetermined level as can be (exhaust air-fuel ratio is considerable so that the rich) to reduce the fuel supply amount when such feedback control of the fuel injection amount of the NO X absorbent during regeneration.

【００３２】また、上記実施例では燃料噴射弁４からの
燃料噴射によりＮＯX 吸収剤に還元剤（燃料）を供給し
ているが別途還元剤供給装置を設けてＮＯX 吸収剤に還
元剤を供給するようにしてもよい。この場合、例えば、
吸気管２のシャッターバルブ６下流側に開口する還元剤
供給ノズルを設け、ＮＯX 吸収剤再生時に吸気管負圧を
利用して吸気管内に還元剤を供給したり、或いはＮＯX
吸収剤上流側の排気管に供給ノズルを設けポンプ等の加
圧手段により排気管内に還元剤を噴射するようにするこ
ともできる。Further, a reducing agent to the NO X absorbent provided although supplying reducing agent (fuel) to the NO X absorbent by the fuel injection separately reducing agent supply device from the fuel injection valve 4 in the above embodiment You may make it supply. In this case, for example,
A reducing agent supply nozzle opening to shutter valve 6 downstream of the intake pipe 2 is provided, and supplies the reducing agent into the intake pipe by using an intake pipe negative pressure during the NO X absorbent regeneration, or NO X
A supply nozzle may be provided in the exhaust pipe on the upstream side of the absorbent, and the reducing agent may be injected into the exhaust pipe by a pressurizing means such as a pump.

【００３３】次に図３に本発明の別の実施例を示す。図
３において、図２の実施例と同一の要素は同じ参照符号
で示している。図２の実施例では、ＥＧＲ通路１１はＮ
ＯX吸収剤１５の上流側の排気通路に接続されていた
が、本実施例ではＥＧＲ通路１１はＮＯX 吸収剤１５の
下流側の排気通路に接続され、ＮＯX 吸収剤１５と排気
シャッターバルブ８との間の部分から吸気側に排気を還
流させている点が図２の実施例と相違している。FIG. 3 shows another embodiment of the present invention. 3, the same elements as those in the embodiment of FIG. 2 are denoted by the same reference numerals. In the embodiment shown in FIG.
O X absorbent 15 had been connected to the exhaust passage upstream of, EGR passage 11 in this embodiment is connected to an exhaust passage downstream of the NO X absorbent 15, the exhaust shutter valve as the NO X absorbent 15 8 differs from the embodiment of FIG. 2 in that exhaust gas is recirculated from the portion between the exhaust gas and the intake air to the intake side.

【００３４】図２の実施例では、例えば吸入圧力の低下
による圧縮不足のためエンジン１で燃焼が生じなかった
ような場合には供給された燃料の全量をＮＯX 吸収剤１
５で燃焼させる必要があり、排気温度等の条件によって
は燃料のＨＣ成分が未燃焼のまま下流側に流出する可能
性がある。本実施例ではＮＯX 吸収剤１５下流側から排
気を取り出して吸気側に還流させるようにしたことによ
り、ＮＯX 吸収剤１５を通過した未燃焼のＨＣ成分を排
気とともに還流させることができ、ＮＯX 吸収剤１５の
再生時に燃料を有効に使用することができる。[0034] In the embodiment of FIG. 2, for example, the total amount of supplied fuel if the engine 1 for compression lack due to a decrease in suction pressure as combustion does not occur the NO X absorbent 1
It is necessary to combust the fuel in step 5, and depending on conditions such as the exhaust gas temperature, there is a possibility that the HC component of the fuel flows out downstream without burning. By adapted to give recirculated to the intake side is taken out of the exhaust from the NO X absorbent 15 downstream in the present embodiment, it is possible to recirculate together with the exhaust of HC components unburned passing through the the NO X absorbent 15, NO The fuel can be used effectively when the X absorbent 15 is regenerated.

【００３５】さらに、図２の実施例では、ＮＯX 吸収剤
１５を通る排気の流れを確保するために、吸気シャッタ
ーバルブ６からある程度の新気を導入し、排気シャッタ
ーバルブ８から新気の量に相当する量の排気を外部に流
出させる必要があるが、本実施例ではＮＯX 吸収剤１５
下流側から排気を取り出して吸気側に還流させるように
したため、吸気シャッターバルブ６から導入する新気の
量にかかわらずＮＯX吸収剤１５を通る排気の流れを確
保することができる。このため、本実施例では、図２の
実施例よりさらに大幅に新気の量を低減することが可能
となり還元剤消費量がさらに低減される利点がある。な
お、本実施例におけるＮＯX 吸収剤１５の再生操作は図
２の実施例と略同一であるため、ここでは説明を省略す
る。Further, in the embodiment of FIG. 2, a certain amount of fresh air is introduced from the intake shutter valve 6 and the amount of fresh air is introduced from the exhaust shutter valve 8 in order to secure the flow of exhaust gas through the NO X absorbent 15. it is necessary to flow out the corresponding amount of the exhaust to the outside, but in this embodiment the NO X absorbent 15
Because you allow recirculated to the intake side from the downstream side is taken out of the exhaust, it is possible to ensure the flow of exhaust through the the NO X absorbent 15 regardless of the amount of fresh air introduced from the intake shutter valve 6. For this reason, in this embodiment, the amount of fresh air can be reduced much more than in the embodiment of FIG. 2, and there is an advantage that the consumption of the reducing agent is further reduced. Since playback operations of the NO X absorbent 15 in this embodiment is substantially the same as the embodiment of FIG. 2, the description thereof is omitted here.

【００３６】以上、本発明の内燃機関の排気浄化装置を
ディーゼルエンジンに適用した場合について説明した
が、本発明はディーゼルエンジンにのみ適用が限定され
るわけではなく、希薄燃焼を行うガソリンエンジン等に
も適用可能であることは言うまでもない。Although the case where the exhaust gas purifying apparatus for an internal combustion engine of the present invention is applied to a diesel engine has been described above, the application of the present invention is not limited only to a diesel engine, but is applied to a gasoline engine or the like which performs lean combustion. Needless to say, this is also applicable.

【００３７】[0037]

【発明の効果】本発明の内燃機関の排気浄化装置は、Ｎ
ＯX 吸収剤の再生操作時に機関排気の少なくとも一部を
機関吸気側に還流させる手段を設けたことにより、機関
潤滑油消費の増大や運転感覚の悪化を生じることなくＮ
ＯX 吸収剤再生時の還元剤消費量の大幅な低減が可能と
なる効果を奏する。The exhaust gas purifying apparatus for an internal combustion engine according to the present invention has N
By providing a means for recirculating at least a part of the engine exhaust to the engine intake side during the regeneration operation of the OX absorbent, the N lubricating oil consumption does not increase and the driving feeling does not deteriorate.
O X absorbent significant reduction of the reducing agent consumption during reproduction the effect that can be achieved.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の排気浄化装置の一実施例を示す図であ
る。FIG. 1 is a view showing one embodiment of an exhaust gas purification apparatus of the present invention.

【図２】ＮＯX 吸収剤のＮＯX 吸放出作用を説明する図
である。FIG. 2 is a diagram illustrating the NO X absorption / release action of a NO X absorbent.

【図３】本発明の排気浄化装置の、図１とは別の実施例
を示す図である。FIG. 3 is a view showing another embodiment of the exhaust gas purification apparatus of the present invention, which is different from FIG.

【符号の説明】[Explanation of symbols]

１…ディーゼルエンジン ２…エンジン吸気管 ３…エンジン排気管 ６…吸気シャッターバルブ ８…排気シャッターバルブ １１…ＥＧＲ通路 １２…ＥＧＲ弁 １５…ＮＯX 吸収剤 ３０…電子制御ユニット1 ... diesel engine 2 ... engine intake pipe 3 ... engine exhaust pipe 6 ... intake shutter valve 8 ... exhaust shutter valve 11 ... EGR passage 12 ... EGR valve 15 ... NO X absorbent 30 ... electronic control unit

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｆ０２Ｄ 9/02 ３４１ Ｆ０２Ｄ 9/02 ３４１Ｇ 9/04 9/04 Ｅ Ｆ０２Ｍ 25/07 ５５０ Ｆ０２Ｍ 25/07 ５５０Ｚ ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 6 Identification number Agency reference number FI Technical display F02D 9/02 341 F02D 9/02 341G 9/04 9/04 E F02M 25/07 550 F02M 25 / 07 550Z

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 リーン空燃比の燃焼を行う内燃機関の排
気通路に、流入排気の空燃比がリーンのときにＮＯX を
吸収し流入排気の酸素濃度が低下したときに吸収したＮ
ＯX を放出するＮＯX 吸収剤を配置して排気中のＮＯX
を吸収させ、前記ＮＯX 吸収剤に還元剤を供給すること
により排気中の酸素濃度を低下させてＮＯX 吸収剤から
吸収したＮＯX を放出させるとともに該ＮＯX を還元浄
化する内燃機関の排気浄化装置において、前記ＮＯX 吸
収剤に還元剤を供給する際に、機関排気の少なくとも一
部を機関吸気通路に還流させる手段を備えたことを特徴
とする内燃機関の排気浄化装置。In an exhaust passage of claim 1 an internal combustion engine causing combustion of lean air-fuel ratio, the air-fuel ratio of the inflowing exhaust gas is the oxygen concentration of the inflowing exhaust absorbs NO X when the lean absorbed when reduced N
NO X absorbent that emits O X is disposed and NO X
To absorb the exhaust of an internal combustion engine with the release of NO X absorbed and thus reduce the oxygen concentration in the exhaust gas the NO X absorbent to reduce and purify the NO X by feeding a reducing agent to the the NO X absorbent in purifier, the NO in the X absorbent when supplying a reducing agent, an exhaust purification device for an internal combustion engine, characterized in that it comprises means for recirculating at least a portion of the engine exhaust to an engine intake passage.
JP5104347A 1993-04-30 1993-04-30 Exhaust gas purification device for internal combustion engine Expired - Lifetime JP2722990B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5104347A JP2722990B2 (en) 1993-04-30 1993-04-30 Exhaust gas purification device for internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5104347A JP2722990B2 (en) 1993-04-30 1993-04-30 Exhaust gas purification device for internal combustion engine

Publications (2)

Publication Number Publication Date
JPH06317142A JPH06317142A (en) 1994-11-15
JP2722990B2 true JP2722990B2 (en) 1998-03-09

Family

ID=14378363

Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
JP (1) JP2722990B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999067511A1 (en) * 1998-06-23 1999-12-29 Toyota Jidosha Kabushiki Kaisha Exhaust emission control device of internal combustion engine

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2943641B2 (en) * 1994-12-21 1999-08-30 トヨタ自動車株式会社 Exhaust gas purification device
JPH0988691A (en) * 1995-09-20 1997-03-31 Toyota Motor Corp Compression ignition internal combustion engine
DE19716275C1 (en) * 1997-04-18 1998-09-24 Volkswagen Ag Process for reducing nitrogen oxide in the exhaust gas of an internal combustion engine
JP3702798B2 (en) * 2001-03-02 2005-10-05 三菱自動車工業株式会社 Catalyst deterioration suppressing device for internal combustion engine
AU2003207213A1 (en) * 2002-02-12 2003-09-04 Isuzu Motors Limited Exhaust gas decontamination system and method of exhaust gas decontamination
JP2007327389A (en) * 2006-06-07 2007-12-20 Mitsubishi Heavy Ind Ltd Exhaust gas treatment device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999067511A1 (en) * 1998-06-23 1999-12-29 Toyota Jidosha Kabushiki Kaisha Exhaust emission control device of internal combustion engine
US6959540B2 (en) 1998-06-23 2005-11-01 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification device of internal combustion engine
US7086222B2 (en) 1998-06-23 2006-08-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification device of internal combustion engine
US7086223B2 (en) 1998-06-23 2006-08-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification device of internal combustion engine
US7272924B2 (en) 1998-06-23 2007-09-25 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification device of internal combustion engine

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